Referring to FIG. 1, a conventional coffee bean roaster 1, as disclosed in Taiwanese Patent Publication No. 201400036, includes a roasting module 11, a collector device 12 connected to the roasting module 11, and a heating module 13 connected to the roasting module 11 and for applying heat to the roasting module 11. The roasting module 11 includes a feed unit 112 and a roller 113 that defines a roasting chamber 111. The roasting chamber 111 has an exhaust opening 10. The collector device 12 has an inlet opening 121 that is in spatial communication with the exhaust opening 10, and an outlet opening 122. Heated air and chaff generated by roasting coffee beans exit the roasting chamber 111 through the exhaust opening 10 and enter into the collector device 12 through the inlet opening 121. The chaff is collected in the collector device 12 and the heated air flows out from the outlet opening 122.
However, the heated air undesirably heats the collector device 12 as the heated air passes through the inlet and outlet openings 121, 122, which makes replacement of the collector device 12 relatively difficult and inconvenient since the collector device 12 is too hot to be touched by hand during or immediately after a roasting operation.